Bazz Fuss Different Sounds

[Nimise]

Hello I am really new to building guitar pedals and a while back I built a bazz fuss(http://www.forrestwhitesides.com/node/42) I believe everything is the same except I used a bat41 diode. The effect works fine but there is something I am curious about concerning its sound. When I plug my guitar directly into the pedal it sounds like a fuzz and if I turn the volume down on my guitar it just starts making farting noises and the notes do not sustain at all, they either come threw or they are completely cut off. On the other hand if I plug my guitar into an ehx metal muff(not engaged) before the bazz fuss it sounds a lot more like an overdrive pedal with more high end. Now if I turn the volume down on my guitar it acts almost like a gain control and I can get a just slightly overdriven sound that responds to how hard I play. Can anyone tell me what is going on here? I know the metal muff is not true bypass but how could it change the characteristics of the bazz fuss so much. Thanks in advance for any insight!

[GibsonGM]

I suspect that the metal muff may have a buffer that is always engaged, even when the pedal is bypassed, the way Boss pedals are set up.

If so, that could account for the effect you're noticing.  A buffer allows the pedal following it to take all the current it wants, instead of being so sensitive re. your volume pedal or anything that came before it (overly simplistic explanation here, but that's kind of the gist of it!  It doesn't affect the impedance when you turn your vol. down).     Lots to learn about this stuff - you're in the right place, and it's a good question!   Read a lot, and ask questions...starting with "buffer", I suppose!   Post again if you want more info.

Happy building, and welcome!  

[ashcat_lt]

If you used the layout as shown in your link, I'd be willing to bet that adding an input cap would help with the farting out issue.  Without it, I think the V control in your guitar is messing with the bias for the transistor.

As for the tonal differences, I think this circuit is one that depends on a lowish input impedance interacting with the inductance from the pickups to cut treble on the way in.  The muff pedal doesn't load the pickups that way, and its output is not inductive, so you get more treble going into the fuzz.

[mth5044]

If you used the layout as shown in your link, I'd be willing to bet that adding an input cap would help with the farting out issue.  Without it, I think the V control in your guitar is messing with the bias for the transistor.

As for the tonal differences, I think this circuit is one that depends on a lowish input impedance interacting with the inductance from the pickups to cut treble on the way in.  The muff pedal doesn't load the pickups that way, and its output is not inductive, so you get more treble going into the fuzz.

The 2.2u is not an input cap?

[ashcat_lt]

Ummm...nm...   

[GibsonGM]

Just for the heck of it, I'd love to know what putting a buffer before the Fuss does...if you have a spare transistor, you could easily make one with just a couple of parts (search). 

[karbomusic]

I know the metal muff is not true bypass but how could it change the characteristics of the bazz fuss so much.

Because it isn't true bypass, it's acting as a buffer, until then the guitar is actually part of the effect circuit hence all the wild interactions. The test you just performed is a very quick and easy way to see if a circuit needs a buffer. In a traditional fuzz face circuit, that same interaction between instrument and circuit (no buffer) causes changes in the circuit we like. If a buffer makes it sound better, as the other's mentioned, add a buffer to the circuit. Simple to do and typically a low parts count:

http://www.muzique.com/lab/buffers.htm

Or as you have experienced, keep some buffered bypass pedal in front of it all the time. In super simple circuits like the one you posted, such anomalies are very likely, that's the reason circuits with less anomalies have more parts much of the time.   It's not that much different than computer programming where getting it to do what you want is usually easy, all the hard labor and extra code is usually to then prevent all the things you don't want to happen.